Solar cell and photovoltaic module

Abstract

The invention relates to the field of photovoltaic technology, in particular to a solar cell and a photovoltaic module, in the solar cell, a cell sheet body is provided with a first surface and a second surface opposite to each other along the thickness direction of the cell sheet body, and a side surface connecting the first surface and the second surface, and the side surface comprises a cutting surface; the first face and the second face respectively comprise a first area close to the cutting face; the first passivation layer is formed on the cutting surface, the first passivation layer further comprises an extension part extending to the first area of the first surface and / or the first area of the second surface, and the extension part comprises first parts located at the two ends and a second part located in the middle in the length direction of the battery piece body; the width of the first part is greater than or equal to that of the second part along the width direction of the cell body. The arrangement of the first passivation layer and the extension part can reduce the recombination rate of photon-generated carriers at the cutting surface and near the cutting surface, and effectively improves the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module. Background Technology

[0002] Currently, after the entire solar cell is fabricated, it is typically sliced ​​into multiple segments, such as two-segment, three-segment, four-segment, eight-segment, and sixteen-segment cells. Interconnecting these segments helps reduce power loss; however, the cut surfaces created by slicing introduce efficiency losses. Passivation technology refers to the method of passivating and repairing damage to the cut surfaces of solar cells after slicing, specifically by applying a passivation layer to the cut surfaces.

[0003] However, charge carriers generated near the cut surface in the solar cell slabs will still move to the cut surface and recombine with defects before being collected by the electrodes, resulting in a loss of solar cell efficiency. Summary of the Invention

[0004] In view of this, the present invention proposes a solar cell and a photovoltaic module, which aims to at least partially solve the technical problem that the efficiency of existing solar cells is greatly reduced after cutting.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: In a first aspect, embodiments of the present invention provide a solar cell, the solar cell comprising: A battery cell body has a first surface and a second surface opposite to each other along its thickness direction, and a side surface connecting the first surface and the second surface, the side surface including a cut surface; the first surface and the second surface each include: a first region near the cut surface; a first passivation layer formed on the cut surface, the first passivation layer further including an extension portion extending to the first region of the first surface and / or the first region of the second surface, the extension portion including a first portion located at both ends and a second portion located in the middle along the length direction of the battery cell body; along the width direction of the battery cell body, the width of the first portion is greater than or equal to the width of the second portion, the width direction is perpendicular to the cut surface, the length direction and the thickness direction are parallel to the cut surface, and the length direction is perpendicular to the thickness direction.

[0006] In some embodiments, along the width direction, the width of the solar cell is W1, the width of the first portion is W2, 3%W1≤W2≤W1; and / or, the width of the second portion is W3, 0<W3≤5%W1; and / or, 3mm≤W2≤105mm; and / or, 0<W3≤6mm; and / or, the solar cell further includes a plurality of current collector electrodes disposed on the first surface and / or the second surface, the plurality of current collector electrodes being spaced apart along the width direction and extending along the length direction, the first portion covering 1 to 150 of the current collector electrodes, and the second portion covering 0 to 5 of the current collector electrodes; and / or, the solar cell further includes a plurality of interconnects, the plurality of interconnects being arrayed on at least one of the first surface and the second surface, the plurality of interconnects including a plurality of first edge interconnects near the cut surface, and the distance between the second portion and any one of the plurality of first edge interconnects along the width direction being greater than or equal to 0.1mm.

[0007] In some embodiments, along the thickness direction, the thickness of the first portion is greater than or equal to the thickness of the second portion; and / or, the thickness of the first portion ranges from 0 to 400 nm, and the thickness of the second portion ranges from 0 nm to 300 nm; and / or, the ratio of the thickness of the first portion to the thickness of the first passivation layer located on the cutting surface ranges from 0.8 to 8, and the ratio of the thickness of the second portion to the thickness of the first passivation layer located on the cutting surface ranges from 0.5 to 5.

[0008] In some embodiments, the first portion includes a first sub-portion and a second sub-portion connected together, the first sub-portion located between the cutting surface and the second sub-portion; the second portion includes a third sub-portion and a fourth sub-portion connected together, the third sub-portion located between the cutting surface and the fourth sub-portion, wherein along the thickness direction, the thickness of the first sub-portion is greater than or equal to the thickness of the second sub-portion; and / or, the thickness of the third sub-portion is greater than or equal to the thickness of the fourth sub-portion; and / or, the thickness of the first sub-portion ranges from 30 nm to 400 nm, and the thickness of the third sub-portion ranges from 20 nm to 300 nm; and / or, the thickness of the first sub-portion is greater than or equal to the thickness of the third sub-portion; and / or, the thickness of the first sub-portion is greater than or equal to the thickness of the first passivation layer located on the cutting surface; and / or, the thickness of the third sub-portion is greater than or equal to the thickness of the first passivation layer located on the cutting surface.

[0009] In some embodiments, along the length direction, the length of the first sub-part is greater than or equal to the length of the second sub-part; and / or, the length of the third sub-part is greater than or equal to the length of the fourth sub-part.

[0010] In some embodiments, the length of the solar cell is L1 along the length direction, and the width of the solar cell is W1 along the width direction, where W1 / L1=n and 0.1≤n≤0.8; the width of the second part is W3, satisfying W3 / W1≤1 / 20n.

[0011] In some embodiments, the side surface further includes a non-cut surface, the non-cut surface including a first non-cut surface and a second non-cut surface perpendicular to the cut surface, the first passivation layer further including a third portion disposed on the first non-cut surface and a fourth portion disposed on the second non-cut surface; the third portion includes a fifth sub-portion and a sixth sub-portion connected together, the fifth sub-portion being between the cut surface and the sixth sub-portion, the fourth portion including a seventh sub-portion and an eighth sub-portion connected together, the seventh sub-portion being located between the cut surface and the eighth sub-portion; wherein, along the thickness direction, the width of the fifth sub-portion is greater than or equal to the width of the sixth sub-portion; and / or, along the length direction, the thickness of the fifth sub-portion is greater than or equal to the thickness of the sixth sub-portion; and / or, along the thickness direction, the width of the seventh sub-portion is greater than or equal to the width of the eighth sub-portion; and / or, along the length direction, the thickness of the seventh sub-portion is greater than or equal to the thickness of the eighth sub-portion.

[0012] In some embodiments, the solar cell further includes a plurality of interconnects arranged in an array on at least one of the first surface and the second surface. The first surface and the second surface each include a second region away from the cut surface. The side surface also includes a first side surface parallel to the cut surface. The plurality of interconnects includes a plurality of second edge interconnects near the first side surface. The solar cell further includes a second passivation layer disposed on the first side surface. The second passivation layer includes an extension portion disposed in the second region. The distance between the extension portion and the plurality of second edge interconnects along the width direction is greater than or equal to 0.1 mm.

[0013] In some embodiments, the solar cell further includes a plurality of interconnects arranged in an array on at least one of the first surface and the second surface, wherein the extension portion does not cover the interconnects.

[0014] In some embodiments, the device further includes: a hydrogen-containing antireflective layer and a surface passivation layer sequentially disposed along the thickness direction from the extension portion toward the battery cell body, wherein the extension portion, the hydrogen-containing antireflective layer, and the surface passivation layer constitute an edge passivation stack.

[0015] In some embodiments, the solar cell further includes: a silicon substrate; a first doped layer and a second doped layer, wherein the first doped layer is disposed on the first surface and the second doped layer is disposed on the second surface, and the first doped layer and the second doped layer have opposite conductivity; a third passivation layer and a fourth passivation layer, wherein the third passivation layer is disposed on the first doped layer and the fourth passivation layer is disposed on the second doped layer; a first antireflection layer and a second antireflection layer, wherein the first antireflection layer is disposed on the third passivation layer and the second antireflection layer is disposed on the fourth passivation layer; and the extension portion covers a portion of the first antireflection layer and a portion of the second antireflection layer.

[0016] In some embodiments, the first surface further includes a third region, the third region having a first step structure recessed into the solar cell along the thickness direction, wherein the first doped layer does not extend into the third region; and / or, the second surface further includes a fourth region, the fourth region having a second step structure recessed into the solar cell along the thickness direction, wherein the second doped layer does not extend into the fourth region.

[0017] In some embodiments, the first doped layer includes first doped segments and first spacer segments arranged at intervals, and the extension portion covers at least one first doped segment and at least one first spacer segment; and / or, the second doped layer includes second doped segments and second spacer segments arranged at intervals, and the extension portion covers at least one second doped segment and at least one second spacer segment.

[0018] In some embodiments, the solar cell further includes: a silicon substrate; a first doped layer and a second doped layer, wherein the first doped layer and the second doped layer are disposed on a second surface, the second surface being the back surface of the solar cell, and the first doped layer and the second doped layer have opposite conductivity; a third passivation layer and a fourth passivation layer, wherein the third passivation layer is disposed on the first surface, and the fourth passivation layer is disposed on the first doped layer and the second doped layer; a first antireflection layer and a second antireflection layer, wherein the first antireflection layer is disposed on the third passivation layer, and the second antireflection layer is disposed on the fourth passivation layer; and the extension portion covers a portion of the first antireflection layer and a portion of the second antireflection layer.

[0019] In some embodiments, the second surface further includes a fourth region, the fourth region having a second step structure recessed into the solar cell along the thickness direction, wherein neither the first doped layer nor the second doped layer extends into the fourth region.

[0020] In some embodiments, the second surface includes a first doped region, a second doped region, and an isolation region located between the two, wherein the first doped layer is disposed in the first doped region, the second doped layer is disposed in the second doped region, and the extended portion covers at least one of the isolation regions.

[0021] In some embodiments, the first surface is a light-facing surface; and / or, the first passivation layer, the third passivation layer, and the fourth passivation layer respectively include one or more combinations of aluminum oxide layer, silicon nitride layer, silicon oxide layer, silicon oxynitride layer, intrinsic amorphous silicon layer, intrinsic microcrystalline silicon layer, doped amorphous silicon layer, doped microcrystalline silicon layer, and doped polycrystalline silicon.

[0022] Secondly, embodiments of the present invention also provide a photovoltaic module, the photovoltaic module including a battery string, an encapsulation layer and a cover plate, wherein the battery string is formed by connecting multiple solar cells as described above; the encapsulation layer is used to cover the surface of the battery string; and the cover plate is used to cover the surface of the encapsulation layer away from the battery string.

[0023] This invention discloses a solar cell. By providing a first passivation layer on the cut surface to passivate the cut surface, and by providing an extension portion in a first region near the cut surface, the recombination rate of photogenerated carriers at and near the cut surface can be reduced. Furthermore, the first surface and / or the second surface corresponding to the first portion are located at the beginning or end of the slicing process. The cell body corresponding to the first portion has more defects than the cell body corresponding to the second portion. Setting the width of the first portion to be greater than or equal to the width of the second portion can further reduce the cutting efficiency loss. Therefore, the provision of the first passivation layer and the first and second portions in the extension portion reduces the recombination of carriers generated by the solar cell near the cut surface with defects on the cut surface, allowing more carriers to be collected by the electrodes and effectively improving the photoelectric conversion efficiency of the solar cell.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0026] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a cross-sectional view of a solar cell according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the solar cell described in the first embodiment of the present invention, from top view. Figure 4 This is a schematic diagram of the structure of the solar cell described in the second embodiment of the present invention, from top view. Figure 5 This is a schematic diagram of the structure of the first non-cut surface according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the solar cell described in the third embodiment of the present invention, from top view. Figure 7 This is a structural schematic diagram of a cross-sectional view of a solar cell according to another embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Battery cell body; 10. First surface; 11. Second surface; 12. Side surface; 13. Cut surface; 14. Non-cut surface; 141. First non-cut surface; 142. Second non-cut surface; 15. First region; 16. Second region; 17. Third region; 18. Fourth region; 19. First side surface; 20. First passivation layer; 21. Extension portion; 22. First portion; 221. First sub-portion; 222. Second sub-portion; 23. Second portion; 231. Third sub-portion; 232. Fourth sub-portion; 24. Third portion; 241. Fifth sub-portion; 242. Sixth sub-portion; 30. Current collector electrode; 40. Interconnector; 41. First edge interconnect; 42. Second edge interconnect; 51. Silicon substrate; 52. First doped layer; 521. First doped segment; 522. First spacer segment; 53. Second doped layer; 531. Second doped segment; 532. Second spacer segment; 54. Third passivation layer; 55. Fourth passivation layer; 56. First antireflection layer; 57. Second antireflection layer; X: length direction; Y: width direction; Z: thickness direction. Detailed Implementation

[0028] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0029] This application provides a solar cell, which includes a cell body 1, as shown in the following embodiment. Figure 1As shown, the battery cell body 1 has a first surface 10 and a second surface 11 opposite each other along its thickness direction Z, and a side surface 12 connecting the first surface 10 and the second surface 11. The side surface 12 includes a cut surface 13 and a non-cut surface 14. The first surface 10 and the second surface 11 each include a first region 15 near the cut surface 13. Further referring to... Figure 2 As shown, the solar cell also includes a first passivation layer 20 formed on the cut surface 13, and the first passivation layer 20 also includes an extension portion 21 extending to the first region 15 of the first surface 10 and / or the first region 15 of the second surface 11; referring again Figure 3 As shown, the extension portion 21 includes a first portion 22 located at both ends and a second portion 23 located in the middle along the length direction X of the battery cell body 1; along the width direction Y of the battery cell body 1, the width of the first portion 22 is greater than or equal to the width of the second portion 23. The width direction Y is perpendicular to the cutting surface 13, the length direction X and the thickness direction Z are parallel to the cutting surface 13, and the length direction X is perpendicular to the thickness direction Z.

[0030] The specific number of slicing units obtained by cutting a whole solar cell is not limited. For example, it can be cut along the center line of the solar cell to obtain two half-cells, or it can be cut twice parallel to the center line to obtain four slicing units. Slicing a whole solar cell into slicing units can reduce current density and resistance loss, thereby improving the power generation efficiency and reliability of photovoltaic modules. However, each slicing unit has a cut surface 13 formed by the cutting, and the cut surface 13 usually inevitably has surface defects and damage. These defects and damages become effective recombination centers for charge carriers, thus affecting the power generation efficiency of the cell.

[0031] The solar cell of this application embodiment reduces the recombination rate of photogenerated carriers at and near the cut surface 13 by providing a first passivation layer 20 on the cut surface 13 and providing an extension portion 21 in the first region 15 near the cut surface 13. Furthermore, the first surface 10 and / or the second surface 11 corresponding to the first portion 22 are located at the beginning or end of the slicing process. The cell body 1 corresponding to the first portion 22 has more defects than the cell body 1 corresponding to the second portion 23. Setting the width of the first portion 22 to be greater than or equal to the width of the second portion 23 can further reduce the cutting efficiency loss. Therefore, the provision of the first passivation layer 20 and the first portion 22 and the second portion 23 in the extension portion 21 allows more carriers generated near the cut surface 13 to be collected by the electrodes, effectively improving the photoelectric conversion efficiency of the solar cell.

[0032] Along the width direction Y, there is a corresponding dimensional relationship between the width of the solar cell, the width of the first part 22, and the width of the second part 23, so as to reduce the cutting efficiency loss introduced by the cutting surface 13, improve the photoelectric conversion efficiency of the solar cell, and avoid appearance and cost problems caused by too many extension parts 21.

[0033] Reference Figure 4 As shown, along the width direction Y, the width of the solar cell is W1, and the width of each first portion 22 is W2, where 3%W1≤W2≤W1. When the first portion 22 is provided on both the first surface 10 and the second surface 11, the widths of the four first portions 22 can be the same or different. When the first portion 22 is provided on either the first surface 10 or the second surface 11, the widths of the two first portions 22 can be the same or different. For example, the width W2 of the first portion 22 can be one of 3%W1, 5%W1, 10%W1, 15%W1, 20%W1, 25%W1, 30%W1, 35%W1, 40%W1, 45%W1, 50%W1, 55%W1, 60%W1, 65%W1, 70%W1, 75%W1, 80%W1, 85%W1, 90%W1, 95%W1, or W1, as well as multiple proportional relationships between the above ratios.

[0034] Reference Figure 4 As shown, along the width direction Y, the width of the second part 23 is W3, where 0 < W3 ≤ 5%W1. When the second part 23 is provided on both the first surface 10 and the second surface 11, the widths of the two second parts 23 can be the same or different. For example, the width W3 of the second part 23 can be one of 0.1%W1, 0.5%W1, 1%W1, 1.5%W1, 2%W1, 2.5%W1, 3%W1, 3.5%W1, 4%W1, 4.5%W1, or 5%W1, as well as multiple proportional relationships between the above proportions.

[0035] Reference Figure 4 As shown, the width W2 of the first part 22 satisfies 3mm≤W2≤105mm. For example, W2 is one of 3mm, 5mm, 10mm, 15mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 105mm, and multiple values ​​between the above values.

[0036] Reference Figure 4As shown, the width W3 of the second part 23 satisfies 0 < W3 ≤ 6 mm. For example, W3 can be one of 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, or multiple values ​​between the above values.

[0037] The first surface 10 and / or the second surface 11 corresponding to the first part 22 are located at the beginning or end of the slicing process. In order to reduce the cutting efficiency loss introduced by slicing and to avoid appearance and cost problems caused by the first part 22 and the second part 23 being too long along the length direction X, there is a corresponding dimensional relationship between the length of the solar cell, the length of the first part 22 and the length of the second part 23.

[0038] Reference Figure 4 As shown, along the length direction X, the length of the solar cell is L1, and the length of each first part 22 is L2, where L2 ≤ 15%L1. The lengths of two or four first parts 22 can be the same or different. For example, the length L2 of each first part 22 can be one of 1%L1, 2%L1, 3%L1, 4%L1, 5%L1, 6%L1, 7%L1, 8%L1, 9%L1, 10%L1, 11%L1, 12%L1, 13%L1, 14%L1, or 15%L1, as well as multiple proportional relationships between the above ratios.

[0039] Reference Figure 4 As shown, along the length direction X, the length of the second part 23 is L3, where L3 ≥ 80%L1. When two second parts 23 are provided, their lengths can be the same or different. For example, the length L3 of the second part 23 can be one of 80%L1, 82%L1, 84%L1, 86%L1, 88%L1, 90%L1, 92%L1, 94%L1, 96%L1, 98%L1, or 99.99%L1, as well as multiple proportional relationships between the aforementioned ratios.

[0040] Reference Figure 4 As shown, L2 ≤ 25%L3, for example, the length L2 of each first part 22 is one of 1%L3, 2%L3, 3%L3, 5%L3, 6%L3, 8%L3, 10%L3, 12%L3, 15%L3, 17%L3, 18%L3, 19%L3, 20%L3, 22%L3, 23%L3, 25%L3, and multiple proportional relationships between the above proportional relationships.

[0041] For different segmented solar cells, such as two-segmented solar cells and three-segmented solar cells, the length L1 and width W1 of the solar cell have the relationship W1 / L1=n, 0.1≤n≤0.8, and W3 / W1≤1 / 20n. In this way, the second part 23 can effectively reduce the recombination rate of photogenerated carriers at and near the cut surface 13, and avoid appearance problems caused by excessive width.

[0042] like Figure 4 As shown, the cut surface 13 is parallel to the length direction X. For sectional solar cells, regardless of whether they are three-section, four-section, six-section, or eight-section, the cut surface 13 is also parallel to the length direction X, and W1 will be further reduced to satisfy W1 < L1. For sectional cells of three sections or more, at least one sectional solar cell has two cut surfaces 13 generated by cutting. The cut surface 13 has a second part with a width of W3, which can reduce recombination caused by cutting defects. The width W3 / W1 ≤ 1 / 20n can avoid appearance problems caused by excessive width and the impact on welding caused by excessive width.

[0043] It is understandable that the thickness of the first passivation layer 20, the thickness of the first portion 22, and the thickness of the second portion 23 will affect the passivation effect and the appearance quality of the solar cell. For example, a thicker passivation layer will appear red, reddish-brown, or green. Therefore, the thickness of the first passivation layer 20, the thickness of the first portion 22, the thickness of the second portion 23, and the proportional relationship between their thicknesses need to be set reasonably to achieve a good passivation effect, reduce the photogenerated carrier recombination rate, and minimize the impact on the appearance of the solar cell.

[0044] Since the battery cell body 1 corresponding to the first part 22 has more defects than the battery cell body 1 corresponding to the second part 23, the thickness of the first part 22 along the thickness direction Z needs to be set to be greater than or equal to the thickness of the second part 23 along the thickness direction Z.

[0045] Along the thickness direction Z, if the thickness of the first part 22 ranges from 0 to 400 nm, then the thickness of the first part 22 is suitable and can achieve a good passivation effect. For example, the thickness of the first part 22 can be one of 0.001 nm, 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or multiple values ​​between the above values.

[0046] Along the thickness direction Z, if the thickness of the second part 23 ranges from 0nm to 300nm, then the thickness of the second part 23 is suitable and can achieve a good passivation effect. For example, the thickness of the second part 23 can be one of 0.001nm, 1nm, 2nm, 5nm, 10nm, 20nm, 30nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, or multiple values ​​between the above values.

[0047] In the width direction Y, if the thickness of the first passivation layer 20 on the cut surface 13 ranges from 10 nm to 120 nm, then the thickness of the first passivation layer 20 on the cut surface 13 is suitable and can achieve a good passivation effect. For example, the thickness of the first passivation layer 20 on the cut surface 13 can be one of 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, or 120 nm, or multiple values ​​between the above values.

[0048] The ratio of the thickness of the first part 22 along the thickness direction Z to the thickness of the first passivation layer 20 located on the cut surface 13 along the width direction Y is in the range of 0.8-8. For example, the ratio of the thickness of the first part 22 to the thickness of the first passivation layer 20 located on the cut surface 13 is one of 0.8, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, and multiple ratios between the above ratios.

[0049] The ratio of the thickness of the second part 23 along the thickness direction Z to the thickness of the first passivation layer 20 on the cut surface 13 along the width direction Y is in the range of 0.5-5. For example, the ratio of the thickness of the second part 23 to the thickness of the first passivation layer 20 on the cut surface 13 is one of 0.5, 0.6, 0.7, 0.8, 1, 1.5, 2, 3, 4, 5, and multiple ratios between the above ratios.

[0050] In some embodiments, refer to Figure 1 and Figure 3 As shown, the solar cell also includes a plurality of current collector electrodes 30 disposed on the first surface 10 and / or the second surface 11. The plurality of current collector electrodes 30 are spaced apart along the width direction Y, and each current collector electrode 30 extends along the length direction X. The first part 22 covers 1 to 150 current collector electrodes 30, and the second part 23 covers 0 to 5 current collector electrodes 30. In this way, the first part 22 and the second part 23 can achieve a better passivation effect, improve the efficiency of the solar cell, and at the same time, the appearance color difference of the solar cell will not be affected by the excessive width of the first part 22 and the second part 23.

[0051] In some embodiments, refer to Figure 3As shown, the solar cell also includes a plurality of interconnects 40, which are arrayed on at least one of the first surface 10 and the second surface 11. The plurality of interconnects 40 include a plurality of first edge interconnects 41 near the cut surface 13. The distance between the second part 23 and any one of the plurality of first edge interconnects 41 along the width direction Y is greater than or equal to 0.1 mm. This makes the second part 23 and the first edge interconnects 41 spaced apart, so as to avoid the second part 23 covering the first edge interconnects 41 due to accuracy error and affecting the welding of the first edge interconnects 41.

[0052] In some embodiments, the extension portion 21 does not cover the interconnect 40, effectively preventing the extension portion 21 from affecting the soldering of the interconnect 40.

[0053] In some embodiments, refer to Figure 6 As shown, the first surface 10 and the second surface 11 also include a second region 16 away from the cut surface 13, and the side surface 12 also includes a first side surface 19 parallel to the cut surface 13. The plurality of interconnects 40 include a plurality of second edge interconnects 42 close to the first side surface 19. The solar cell also includes a second passivation layer disposed on the first side surface 19. The second passivation layer includes an extension portion disposed in the second region 16. The distance between the extension portion and the plurality of second edge interconnects 42 in the width direction Y is greater than or equal to 0.1 mm.

[0054] In this embodiment, the first side surface 19 can be a cut surface or a non-cut surface. The second passivation layer can achieve a passivation effect. The second passivation layer on the first side surface 19 and the extended portion on the second region 16 can reduce the recombination rate of photogenerated carriers at and near the first side surface 19, allowing more carriers to be collected by the electrodes and effectively improving the photoelectric conversion efficiency of the solar cell. Moreover, the extended portion and the multiple second edge interconnects 42 are spaced apart along the width direction Y to prevent the extended portion from covering the second edge interconnects 42 due to precision errors, thus affecting the welding of the second edge interconnects 42.

[0055] It is understandable that the first region 15 and the second region 16 are virtual regions, rather than actual regions or regions set on the first surface 10 and / or the second surface 11. It is easy to understand that the first region 15 and the second region 16 are used to describe more clearly, without limiting the structure of the solar cell.

[0056] In some embodiments, refer to Figure 3As shown, the first part 22 includes a first sub-part 221 and a second sub-part 222 connected together, with the first sub-part 221 located between the cutting surface 13 and the second sub-part 222; the second part 23 includes a third sub-part 231 and a fourth sub-part 232 connected together, with the third sub-part 231 located between the cutting surface 13 and the fourth sub-part 232.

[0057] Since the first sub-part 221 is closer to the cut surface 13 than the second sub-part 222, the thickness of the first sub-part 221 is set to be greater than or equal to the thickness of the second sub-part 222 along the thickness direction Z. Furthermore, the length of the first sub-part 221 is greater than or equal to the length of the second sub-part 222 along the length direction X. In this way, the first sub-part 221 can be better passivated, reducing the recombination rate near the cut surface 13, thereby improving the photoelectric conversion efficiency of the solar cell and avoiding the impact of the overall thickness of the first sub-part 22 on the appearance of the solar cell.

[0058] Since the third sub-part 231 is closer to the cutting surface 13 than the fourth sub-part 232, the thickness of the third sub-part 231 is set to be greater than or equal to the thickness of the fourth sub-part 232 along the thickness direction Z. Furthermore, the length of the third sub-part 231 is greater than or equal to the length of the fourth sub-part 232 along the length direction X. In this way, the third sub-part 231 can be better passivated, reducing the recombination rate near the cutting surface 13, thereby improving the photoelectric conversion efficiency of the solar cell and avoiding the impact of the overall thickness of the second sub-part 23 on the appearance of the solar cell.

[0059] The first sub-part 221 is closer to the beginning or end of the solar cell than the third sub-part 231. The cell body 1 corresponding to the first sub-part 221 has more defects than the cell body 1 corresponding to the third sub-part 231. Therefore, the thickness of the first sub-part 221 can be set to be greater than or equal to the thickness of the third sub-part 231 to passivate according to the defect situation.

[0060] If the thickness of the first sub-part 221 is in the range of 30nm-400nm, then the thickness of the first sub-part 221 is suitable and can achieve a good passivation effect. For example, the thickness of the first sub-part 221 can be one of 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, or 400nm, or multiple values ​​between the above values.

[0061] If the thickness of the third sub-part 231 is in the range of 20nm-300nm, then the thickness of the third sub-part 231 is suitable and can achieve a good passivation effect. For example, the thickness of the third sub-part 231 can be one of 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, or 300nm, or multiple values ​​between the above values.

[0062] In order to better reduce the recombination rate of photogenerated carriers near the cut surface 13, the thickness of the first sub-part 221 is greater than or equal to the thickness of the first passivation layer 20 located on the cut surface 13; the thickness of the third sub-part 231 is greater than or equal to the thickness of the first passivation layer 20 located on the cut surface 13.

[0063] To further improve the passivation effect and reduce the recombination rate of photogenerated carriers near the cut surface 13, a passivation layer is also formed on the non-cut surface 14. (Refer to...) Figure 1 As shown, the non-cutting surface 14 includes a first non-cutting surface 141 and a second non-cutting surface 142 perpendicular to the cutting surface 13, further referring to... Figure 5 As shown, the first passivation layer 20 also includes a third portion 24 disposed on the first non-cut surface 141 and a fourth portion disposed on the second non-cut surface 142.

[0064] In the third part 24, there are two connected sub-parts: a fifth sub-part 241 and a sixth sub-part 242. The fifth sub-part 241 is located between the cutting surface 13 and the sixth sub-part 242, and is closer to the cutting surface. Along the thickness direction Z, the width of the fifth sub-part 241 is greater than or equal to that of the sixth sub-part 242. This results in a larger coverage area of ​​the fifth sub-part 241 in the width direction Z, allowing for better passivation and avoiding the impact of an overly wide third part 24 on the appearance of the first non-cutting surface 141. Along the length direction X, the thickness of the fifth sub-part 241 is greater than or equal to that of the sixth sub-part 242. The greater thickness of the fifth sub-part 241 allows for better passivation, reducing the recombination rate of photogenerated carriers near the cutting surface 13, and also avoiding the impact of an overly thick third part 24 on the appearance of the first non-cutting surface 141.

[0065] The fourth part includes a connected seventh sub-part and an eighth sub-part. The seventh sub-part is located between the cutting surface 13 and the eighth sub-part. The seventh sub-part is closer to the cutting surface. Along the thickness direction Z, the width of the seventh sub-part is greater than or equal to that of the eighth sub-part. Thus, the seventh sub-part has a larger coverage area in the width direction Z, which allows it to achieve a better passivation effect and avoids the overall width of the fourth part from affecting the appearance on the second non-cutting surface 142. Along the length direction X, the thickness of the seventh sub-part is greater than or equal to that of the eighth sub-part. The greater thickness of the seventh sub-part allows for better passivation, reduces the recombination rate of photogenerated carriers near the cutting surface 13, and also avoids the overall thickness of the fourth part from affecting the appearance on the second non-cutting surface 142.

[0066] In some embodiments, the solar cell further includes a hydrogen-containing antireflection layer and a surface passivation layer sequentially disposed along the thickness direction Z from the extension portion 21 toward the cell body 1, wherein the extension portion 21, the hydrogen-containing antireflection layer, and the surface passivation layer constitute an edge passivation stack. In this embodiment, the edge passivation stack can better passivate the cells, further reducing the recombination rate of photogenerated carriers at and near the cut surface 13, thereby improving the photoelectric conversion efficiency of the solar cell. Furthermore, the hydrogen-containing antireflection layer also enables the edge passivation stack to have a hydrogen passivation effect, further improving the photoelectric conversion efficiency.

[0067] The solar cell provided in this application embodiment can be a bifacial cell. In the case of a bifacial solar cell, refer to... Figure 3 As shown, the solar cell also includes a silicon substrate 51, a first doped layer 52, a second doped layer 53, a third passivation layer 54, a fourth passivation layer 55, a first antireflection layer 56, and a second antireflection layer 57. The first doped layer 52 is disposed on the first surface 10, and the second doped layer 53 is disposed on the second surface 11. The first doped layer 52 and the second doped layer 53 have opposite conductivity. The third passivation layer 54 is disposed on the first doped layer 52, and the fourth passivation layer 55 is disposed on the second doped layer 53. The first antireflection layer 56 is disposed on the third passivation layer 54, and the second antireflection layer 57 is disposed on the fourth passivation layer 55. The extension portion 21 covers a portion of the first antireflection layer 56 and a portion of the second antireflection layer 57. Due to the typically large number of defects on the cut surface, the thickness of the first passivation layer 20 is greater than the thickness of the third passivation layer 54 and the fourth passivation layer 55.

[0068] In some embodiments, the first surface 10 further includes a third region 17, which has a first step structure recessed into the solar cell along the thickness direction Z, and the first doped layer 52 does not extend into the third region 17; the second surface 11 further includes a fourth region 18, which has a second step structure recessed into the solar cell along the thickness direction Z, and the second doped layer 53 does not extend into the fourth region 18.

[0069] In this embodiment, the arrangement of the third region 17 and the fourth region 18 can prevent the first doped layer 52 from being connected to the cut surface 13 and the second doped layer 53 from being connected to the cut surface 13 and thus prevent the charge carriers (including electrons and holes) from moving to the cut surface 13 and recombinating with defects before being collected by the electrode, thereby improving the efficiency of the solar cell.

[0070] In some embodiments, the first doped layer 52 includes first doped segments 521 and first spacer segments 522 arranged at intervals, and the extension portion 21 covers at least one first doped segment 521 and at least one first spacer segment 522. And / or, the second doped layer 53 includes second doped segments 531 and second spacer segments 532 arranged at intervals, and the extension portion 21 covers at least one second doped segment 531 and at least one second spacer segment 532.

[0071] The first doped segment 521 refers to the region in the first doped layer 52 where polysilicon is doped, and the first spacer segment 522 refers to the region in the first doped layer 52 where polysilicon is not doped. The second doped segment 531 refers to the region in the second doped layer 53 where polysilicon is doped, and the second spacer segment 532 refers to the region in the second doped layer 53 where polysilicon is not doped. In this embodiment, by providing a first spacer segment 522 without polysilicon in the first doped layer 52 and a second spacer segment 532 without polysilicon in the second doped layer 53, the parasitic absorption of light by the doped polysilicon can be reduced, especially in the near-infrared band, which can be effectively reflected back to the silicon substrate, thereby improving the photoelectric conversion efficiency of the solar cell.

[0072] The solar cell provided in this application embodiment can also be a back-contact cell. In the case where the solar cell is a back-contact cell, refer to... Figure 7 As shown, the solar cell includes a silicon substrate 51, a first doped layer 52, a second doped layer 53, a third passivation layer 54, a fourth passivation layer 55, a first antireflection layer 56, and a second antireflection layer 57. The first doped layer 52 and the second doped layer 53 are disposed on a second surface 11, which is the back surface of the solar cell. The first doped layer 52 and the second doped layer 53 have opposite conductivity. The third passivation layer 54 is disposed on a first surface 10, and the fourth passivation layer 55 is disposed on the first doped layer 52 and the second doped layer 53. The first antireflection layer 56 is disposed on the third passivation layer 54, and the second antireflection layer 57 is disposed on the fourth passivation layer 55. An extension portion 21 covers portions of the first antireflection layer 56 and portions of the second antireflection layer 57.

[0073] In some embodiments, the second surface 11 further includes a fourth region 18, which has a second stepped structure recessed into the solar cell along the thickness direction Z. Neither the first doped layer 52 nor the second doped layer 53 extends into the fourth region 18. In this embodiment, the fourth region 18 avoids the first doped layer 52 and the second doped layer 53 from connecting with the cut surface 13, thus preventing further cutting efficiency loss. This also prevents charge carriers from moving to the cut surface 13 and recombinating with defects before being collected by the electrodes, thereby improving the efficiency of the solar cell.

[0074] In some embodiments, the second surface 11 includes a first doped region, a second doped region, and an isolation region located between the two, a first doped layer 52 disposed in the first doped region, a second doped layer 53 disposed in the second doped region, and an extension portion 21 covering at least one isolation region.

[0075] The first and second doped regions are areas with doped polysilicon, while the isolation region refers to the area without doped polysilicon. In this embodiment, when the entire backlight surface is covered by a doped semiconductor layer, a large amount of parasitic absorption of light occurs, thus reducing the light utilization efficiency. In this embodiment, by setting an isolation region without doped polysilicon, the parasitic absorption of light by the doped semiconductor layer can be reduced, especially in the near-infrared band, where light can be effectively reflected back to the silicon substrate. This increases the light utilization rate of the backlight surface, thereby improving the photoelectric conversion efficiency of the solar cell.

[0076] In the solar cell of this application embodiment, the first surface 10 is the light-facing surface and the second surface 11 is the back-lighting surface.

[0077] It is understandable that the specific materials of the first passivation layer 20, the second passivation layer, the third passivation layer 54, and the fourth passivation layer 55 can be set according to the application requirements. For example, the first passivation layer 20, the second passivation layer, the third passivation layer 54, and the fourth passivation layer 55 may respectively include one or more combinations of aluminum oxide layer, silicon nitride layer, silicon oxide layer, silicon oxynitride layer, intrinsic amorphous silicon layer, intrinsic microcrystalline silicon layer, doped amorphous silicon layer, doped microcrystalline silicon layer, and doped polycrystalline silicon. For example, the first passivation layer 20 may be an aluminum oxide layer, which has excellent passivation performance and can effectively reduce dangling bonds and defects at and near the cut surface 13. Alternatively, the first passivation layer 20 may be a stack of aluminum oxide layer and silicon oxide layer, wherein the silicon oxide layer is located between the aluminum oxide layer and the cut surface 13. Since there are usually too many defects at the cut surface, the thickness of the first passivation layer 20 is greater than the thickness of the third passivation layer 54 and the fourth passivation layer 55.

[0078] This application also provides a photovoltaic module, which includes a battery string, an encapsulation layer, and a cover plate. The battery string is formed by connecting multiple solar cells as described above. The encapsulation layer is used to cover the surface of the battery string. The cover plate is used to cover the surface of the encapsulation layer away from the battery string. Since this photovoltaic module includes the aforementioned solar cells, it also has the same or similar beneficial effects as the photovoltaic modules described above, and will not be repeated here to avoid repetition.

[0079] In this battery string, adjacent solar cells are connected by conductive elements. These conductive elements pass through the cut surface 13 of the solar cells; that is, the conductive element on one solar cell passes through the plane containing the cut surface 13 and connects to the next adjacent solar cell. The first passivation layer 20 located on the cut surface 13, and the extension portion 21 on the first surface 10 and / or the second surface 11, have a good passivation effect, which can prevent the risk of microcracks appearing at the edges of the solar cells due to stress release caused by the connection through the conductive elements. In addition, the contact between the conductive elements and the first passivation layer 20 and the extension portion 21 of the solar cells can reduce the risk of leakage.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For embodiments of devices, electronic devices, computer-readable storage media, and computer program products containing instructions, the descriptions are relatively simple because they are basically similar to the method embodiments; relevant parts can be referred to the descriptions of the method embodiments.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A solar cell, characterized in that, The solar cell includes: A battery cell body (1) has a first surface (10) and a second surface (11) opposite each other along its thickness direction (Z), and a side surface (12) connecting the first surface (10) and the second surface (11), the side surface (12) including a cut surface (13); the first surface (10) and the second surface (11) each include a first region (15) near the cut surface (13); A first passivation layer (20) is formed on the cut surface (13), the first passivation layer (20) further comprising an extension (21) of the first region (15) extending to the first surface (10) and / or an extension of the first region (15) of the second surface (11); and Multiple interconnects (40) are arrayed on at least one of the first surface (10) and the second surface (11), the extension (21) does not cover the interconnects (40), the length direction (X) and the thickness direction (Z) are parallel to the cut surface (13), and the length direction (X) is perpendicular to the thickness direction (Z).

2. The solar cell according to claim 1, characterized in that, The extension portion (21) includes a first portion (22) located at both ends and a second portion (23) located in the middle along the length direction (X) of the battery cell body (1). Along the width direction (Y) of the battery cell body (1), the width of the first portion (22) is greater than the width of the second portion (23), and the width direction (Y) is perpendicular to the cut surface (13). Along the length direction (X), the length of the battery cell body (1) is L1, the length of a single first part (22) is L2, and L2≤15%L1; along the length direction (X), the length of the second part (23) is L3, and L3≥80%L1.

3. The solar cell according to claim 1, characterized in that, The extension portion (21) includes a first portion (22) located at both ends and a second portion (23) located in the middle along the length direction (X) of the cell body (1). Along the width direction (Y), the width of the solar cell is W1, the width of the first portion (22) is W2, 3%W1≤W2≤W1; and / or, the width of the second portion (23) is W3, 0<W3≤5%W1; and / or, 3mm≤W2≤105mm; and / or, 0<W3≤6mm; and / or, The solar cell further includes a plurality of current collector electrodes (30) disposed on the first surface (10) and / or the second surface (11), the plurality of current collector electrodes (30) being spaced apart along the width direction (Y) and extending along the length direction (X), the first portion (22) covering 1 to 150 of the current collector electrodes (30), and the second portion (23) covering 0 to 5 of the current collector electrodes (30); and / or, The solar cell further includes a plurality of interconnects (40), which are arrayed on at least one of the first surface (10) and the second surface (11). The plurality of interconnects (40) include a plurality of first edge interconnects (41) near the cut surface (13). The distance between the second portion (23) and any one of the plurality of first edge interconnects (41) along the width direction (Y) is greater than or equal to 0.1 mm. The width direction (Y) is perpendicular to the cutting surface (13).

4. The solar cell according to claim 1, characterized in that, The extension portion (21) includes a first portion (22) located at both ends along the length direction (X) of the battery cell body (1) and a second portion (23) located in the middle, along the thickness direction (Z). The thickness of the first portion (22) is greater than or equal to the thickness of the second portion (23); and / or, The first portion (22) has a thickness range of 0-400 nm, and the second portion (23) has a thickness range of 0 nm-300 nm; and / or, The ratio of the thickness of the first part (22) to the thickness of the first passivation layer (20) on the cut surface (13) is in the range of 0.8-8, and the ratio of the thickness of the second part (23) to the thickness of the first passivation layer (20) on the cut surface (13) is in the range of 0.5-5.

5. The solar cell according to claim 1, characterized in that, The extension portion (21) includes a first portion (22) located at both ends and a second portion (23) located in the middle along the length direction (X) of the battery cell body (1). The first portion (22) includes a first sub-part (221) and a second sub-part (222) connected together. The first sub-part (221) is located between the cut surface (13) and the second sub-part (222). The second portion (23) includes a third sub-part (231) and a fourth sub-part (232) connected together. The third sub-part (231) is located between the cut surface (13) and the fourth sub-part (232) along the thickness direction (Z). The thickness of the first sub-part (221) is greater than or equal to the thickness of the second sub-part (222); and / or, The thickness of the third sub-part (231) is greater than or equal to the thickness of the fourth sub-part (232); and / or, The thickness of the first sub-part (221) ranges from 30 nm to 400 nm, and the thickness of the third sub-part (231) ranges from 20 nm to 300 nm; and / or, The thickness of the first sub-part (221) is greater than or equal to the thickness of the third sub-part (231); and / or, The thickness of the first sub-part (221) is greater than or equal to the thickness of the first passivation layer (20) located on the cut surface (13); and / or, The thickness of the third sub-part (231) is greater than or equal to the thickness of the first passivation layer (20) located on the cut surface (13).

6. The solar cell according to claim 5, characterized in that, Along the length direction (X), the length of the first sub-part (221) is greater than or equal to the length of the second sub-part (222); and / or, The length of the third sub-part (231) is greater than or equal to the length of the fourth sub-part (232).

7. The solar cell according to claim 1, characterized in that, The extension portion (21) includes a first portion (22) located at both ends along the length direction (X) of the battery cell body (1) and a second portion (23) located in the middle. Along the length direction (X), the length of the solar cell is L1, and along the width direction (Y), the width of the solar cell is W1, W1 / L1=n, 0.1≤n≤0.8; The width of the second part (23) is W3, which satisfies that W3 / W1≤1 / 20n; where, The width direction (Y) is perpendicular to the cutting surface (13).

8. The solar cell according to claim 1, characterized in that, The side surface (12) also includes a non-cut surface (14), which includes a first non-cut surface (141) and a second non-cut surface (142) perpendicular to the cut surface (13). The first passivation layer (20) also includes a third portion (24) disposed on the first non-cut surface (141) and a fourth portion disposed on the second non-cut surface (142). The third part (24) includes a fifth sub-part (241) and a sixth sub-part (242) connected together, the fifth sub-part (241) being between the cutting surface (13) and the sixth sub-part (242); the fourth part includes a seventh sub-part and an eighth sub-part connected together, the seventh sub-part being between the cutting surface (13) and the eighth sub-part. Wherein, along the thickness direction (Z), the width of the fifth sub-part (241) is greater than or equal to that of the sixth sub-part (242); and / or, Along the length direction (X), the thickness of the fifth sub-part (241) is greater than or equal to the thickness of the sixth sub-part (242); and / or, Along the thickness direction (Z), the width of the seventh sub-part is greater than or equal to the width of the eighth sub-part; and / or, Along the length direction (X), the thickness of the seventh sub-part is greater than or equal to the thickness of the eighth sub-part.

9. The solar cell according to claim 1, characterized in that, The solar cell further includes a plurality of interconnects (40), which are arrayed on at least one of the first surface (10) and the second surface (11). The first surface (10) and the second surface (11) also include a second region (16) away from the cut surface (13). The side surface (12) also includes a first side surface (19) parallel to the cut surface (13). The plurality of interconnects (40) includes a plurality of second edge interconnects (42) near the first side surface (19). The solar cell also includes a second passivation layer disposed on the first side surface (19). The second passivation layer includes an extension portion disposed in the second region (16). The distance between the extension portion and the plurality of second edge interconnects (42) in the width direction (Y) is greater than or equal to 0.1 mm. The width direction (Y) is perpendicular to the cutting surface (13).

10. The solar cell according to claim 1, characterized in that, Also includes: A hydrogenated antireflection layer and a surface passivation layer are sequentially arranged in the direction pointing from the extension part (21) to the battery cell body (1) along the thickness direction (Z), and the extension part (21), the hydrogenated antireflection layer, and the surface passivation layer form an edge passivation stack.

11. The solar cell according to claim 1, characterized in that, The solar cell further includes: a silicon substrate (51), a first doping layer (52) and a second doping layer (53), wherein the first doping layer (52) is disposed on the first surface (10), the second doping layer (53) is disposed on the second surface (11), and the first doping layer (52) and the second doping layer (53) have opposite conductivities; a third passivation layer (54) and a fourth passivation layer (55), wherein the third passivation layer (54) is disposed on the first doping layer (52), and the fourth passivation layer (55) is disposed on the second doping layer (53); a first antireflection layer (56) and a second antireflection layer (57), wherein the first antireflection layer (56) is disposed on the third passivation layer (54), and the second antireflection layer (57) is disposed on the fourth passivation layer (55); The extension part (21) covers a part of the first antireflection layer (56) and a part of the second antireflection layer (57).

12. The solar cell according to claim 11, characterized in that, The first surface (10) further includes a third region (17), and the third region (17) is provided with a first stepped structure that is recessed into the solar cell along the thickness direction (Z), and the first doping layer (52) does not extend into the third region (17); and / or, The second surface (11) further includes a fourth region (18), and the fourth region (18) is provided with a second stepped structure that is recessed into the solar cell along the thickness direction (Z), and the second doping layer (53) does not extend into the fourth region (18).

13. The solar cell according to claim 11, characterized in that, The first doping layer (52) includes first doping segments (521) and first spacer segments (522) arranged at intervals, and the extension part (21) covers at least one of the first doping segments (521) and at least one of the first spacer segments (522); and / or, The second doping layer (53) includes second doping segments (531) and second spacer segments (532) arranged at intervals, and the extension part (21) covers at least one of the second doping segments (531) and at least one of the second spacer segments (532).

14. The solar cell according to claim 1, characterized in that, It further includes: a silicon substrate (51), a first doping layer (52) and a second doping layer (53), wherein the first doping layer (52) and the second doping layer (53) are disposed on the second surface (11), and the second surface (11) is the backlight surface of the solar cell, and the first doping layer (52) and the second doping layer (53) have opposite conductivities; a third passivation layer (54) and a fourth passivation layer (55), wherein the third passivation layer (54) is disposed on the first surface (10), and the fourth passivation layer (55) is disposed on the first doping layer (52) and the second doping layer (53); A first antireflection layer (56) and a second antireflection layer (57), wherein the first antireflection layer (56) is disposed on the third passivation layer (54) and the second antireflection layer (57) is disposed on the fourth passivation layer (55); The extension portion (21) covers a portion of the first antireflective layer (56) and a portion of the second antireflective layer (57).

15. The solar cell according to claim 14, characterized in that, The second surface (11) also includes a fourth region (18), which is provided with a second step structure recessed into the solar cell along the thickness direction (Z), and neither the first doped layer (52) nor the second doped layer (53) extends into the fourth region (18).

16. The solar cell according to claim 14, characterized in that, The second surface (11) includes a first doped region, a second doped region and an isolation region located between them, the first doped layer (52) is disposed in the first doped region, the second doped layer (53) is disposed in the second doped region, and the extension portion (21) covers at least one of the isolation regions.

17. The solar cell according to any one of claims 11 to 16, characterized in that, The first surface (10) is a light-facing surface; and / or, The first passivation layer (20), the third passivation layer (54), and the fourth passivation layer (55) respectively include one or more combinations of aluminum oxide layer, silicon nitride layer, silicon oxide layer, silicon oxynitride layer, intrinsic amorphous silicon layer, intrinsic microcrystalline silicon layer, doped amorphous silicon layer, doped microcrystalline silicon layer, and doped polycrystalline silicon.

18. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in any one of claims 1-17; An encapsulation layer is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulation layer away from the battery string.

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